In the drilling and production of oil from subterranean formations water zones are often encountered. Control of these water zones is required in order that the drilling and production may proceed.
Plastics have been used for many years as a means of controlling water zones. Plastics have many advantages for this use. One advantage is that they can be used in a low viscosity form which is capable of completely permeating the open pores of the formation. Another advantage is that they can be reacted in a manner to form a solid, infusible mass having excellent strength and plugging characteristics. Furfuryl alcohol plastics are examples of this type of plastic. The primary disadvantage of this type of plastic is that the polymerization is effected by a catalyst system. Difficulties are encountered in catalyzing the plastic so that it is most effective. One method of catalyzing the polymerizable materials is to inject the catalyst system as a separate fluid after the polymerizable material has been injected. This method has the disadvantage that the catalyst tends to displace the plastic away from the wellbore, thereby reopening some of the flow passages. Another method of catalyzing the ploymerizable material is to add a delayed acting catalyst prior to pumping the polymerizable material into the wellbore. This method has the disadvantage that often times polymerization occurs before the polymerization mass has been injected into the formation, thereby causing insufficient sealing of the formation.
My invention overcomes the disadvantages associated with the methods described in the foregoing.